The long-range goal of this work is to obtain a better understanding of the factors in human cell mediated immunity which are important in organ allotransplantation. This will be pursued by further investigating the relationship between the membrane antigen beta 2 microglobulin (beta 2m) and HL-A and their relationship to the mixed leukocyte culture (MLC) reaction and cell mediated lympholysis (CML). In addition we will continue our investigations into the relationship between MLC and CML by using T and B lymphoblast cell lines as stimulators and targets. Also, we will continue our work with the parents of combined immune deficiency children to determine if any immunological defects can be detected using MLC and CML.